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Journal of Zhejiang University-SCIENCE B (Biomedicine & Biotechnology)  2009, Vol. 10 Issue (7): 512-521    DOI: 10.1631/jzus.B0820300
Biomedicine     
Protective effect of DNA-mediated immunization with liposome-encapsulated GRA4 against infection of Toxoplasma gondii
Rui CHEN, Shao-hong LU, Qun-bo TONG, Di LOU, Dong-yan SHI, Bing-bing JIA, Guo-ping HUANG, Jin-fu WANG
College of Life Sciences, Zhejiang University, Hangzhou 310058, China; Institute of Parasitology, Zhejiang Academy of Medical Science, Hangzhou 310013, China
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Abstract  The dense granule protein 4 (GRA4) is a granular protein from Toxoplasma gondii, and is a candidate for vaccination against this parasite. In this study, the plasmid pcDNA3.1-GRA4 (pGRA4), encoding for the GRA4 antigen, was incorporated by the dehydration-rehydration method into liposomes composed of 16 mmol/L egg phosphatidylcholine (PC), 8 mmol/L dioleoyl phosphatidylethanolamine (DOPE), and 4 mmol/L 1,2-diodeoyl-3-(trimethylammonium) propane (DOTAP). C57BL/6 mice and BALB/c mice were immunized intramuscularly three times with liposome-encapsulated pGRA4 to determine whether DNA immunization could elicit a protective immune response to T. gondii. Enzyme-linked immunosorbent assay (ELISA) of sera from immunized mice showed that liposome-encapsulated pGRA4 generated high levels of IgG antibodies to GRA4. Production of primary interferon (IFN)-γ and interleukin (IL)-2 in GRA4-stimulated splenocytes from vaccinated mice suggested a modulated Th1-type response. 72.7% of C57BL/6 mice immunized with liposome-encapsulated pGRA4 survived the challenge with 80 tissue cysts of ME49 strain, whereas C57BL/6 mice immunized with pGRA4 had only a survival rate of 54.5%. When immunized BALB/c mice were intraperitoneally challenged with 103 tachyzoites of the highly virulent RH strain, the survival time of mice immunized with liposome-encapsulated pGRA4 was markedly longer than that of other groups. Our observations show that liposome-encapsulated pGRA4 enhanced the protective effect against infection of T. gondii.

Key wordsDNA vaccine      Granule protein 4 (GRA4)      Liposome      Toxoplasma gondii     
Received: 24 September 2008     
CLC:  R382.5  
Cite this article:

Rui CHEN, Shao-hong LU, Qun-bo TONG, Di LOU, Dong-yan SHI, Bing-bing JIA, Guo-ping HUANG, Jin-fu WANG. Protective effect of DNA-mediated immunization with liposome-encapsulated GRA4 against infection of Toxoplasma gondii. Journal of Zhejiang University-SCIENCE B (Biomedicine & Biotechnology), 2009, 10(7): 512-521.

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http://www.zjujournals.com/xueshu/zjus-b/10.1631/jzus.B0820300     OR     http://www.zjujournals.com/xueshu/zjus-b/Y2009/V10/I7/512

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